PROCESS FOR PRODUCING 1,1,1,3,3-PENTAFLUOROPROPANE AND/OR 1,1,3,3,3-PENTAFLUOROPROPENE

Abstract: A process for producing 1,1,1,3,3-pentafluoropropane by reducing 1,1,1,3,3,3-pentafluoropropene with hydrogen in the presence of a palladium catalyst in vapor phase at 40 to 300 °C. A process for producing 1,1,1,3,3-pentafluoropropane and/or 1,1,3,3,3-pentafluoropropene by hydrogenating 2-chloro-1,1,3,3,3-pentafluoropropene in the presence of a catalyst comprising at least one member selected from palladium, platinum and rhodium at a temperature of particularly 30 to 450 °C. A process for producing 1,1,3,3,3-pentafluoropropene by dechlorinating 1,1,1,3,3-pentafluoro-2,3-dichloropropane with hydrogen in the presence of a metal oxide catalyst. These processes can provide 1,1,1,3,3-pentafluoropropane and/or 1,1,3,3,3-pentafluoropropene in high yields.

Description: This invention relates to a method of producing a useful compound of 1,1,1,3,3-pentafluoropropane which can be substituted for CFCs and HCFCs which are used as refrigerants, blowing agents and cleaning agents Prior art As a production method of 1,1,1,3,3-pentafluoropropane, it is known that 2,2,3-trichloro-1,1,1,3,3-pentafluoropropane is reduced by hydrogen by using a palladium catalyst (US-A-2942036). The known method, however, is not suitable for producing 1,1,1, 3,3-pentafluoropane industrially because the yield of the product is low due to the formation of a large amount of 1,1,3,3,3-pentafluoropropene and 2-chloro-1,1,3,3,3-pentafluoropropene as by-products. Another method is also known in which 1,1,3,3,3-pentafluoropropene is reduced by hydrogen at room temperature by using a palladium catalyst carried on alumina (Bull. Acad. Sci. USSR Div. Chem. Sci. (Eng.Transl.) 1312 (1960) and Chemical Abstracts, vol. 55, no. 1, abs. no. 349 f (1961), respectively). In this known method, however, the yield of the target product of 1,1,1,3,3-pentafluoropropane is as low as about 70 percent. 1,1,3,3,3-pentafluoropropene used as a starting material in the present invention is a useful compound which can also be used as a raw material in producing various kinds of resins and as an intermediate in producing some medicines or agricultural chemicals, as well as a raw material of HFC blowing agents which do not destroy the ozone layer. So far it is known that 1,1,3,3,3-pentafluoropropene can be synthesised by dehydrochlorination of 1,1,1,3,3-pentafluoro-3-chloropropane with a base (J. Am. Chem. Soc., 68 496(1946)). In this known reaction, however, it is difficult to obtain the raw material and there are many problems in using the reaction industrially as a synthetic method of producing 1,1,3,3,3-pentafluoropropene. Further, there is a known method of using decarboxylation of a potassium salt of a-hydroperfluoro-isobuthylate. In this method, however, it is difficult to obtain the raw material and it is difficult to use the decarboxylation reaction itself industrially (Synthesis of Fluoroorganic Compounds, I. L. Knunyants and G. G. Yakobson, Springer-Verlag, Berlin, Heidelberg, p.8 (1985)). Besides, there is also a known method of using dehydro-iodination of 3-iodo-1,1,1,3,3-pentafluoropropane, but again, it is difficult to obtain a large amount of the raw material at low cost (do., Synthesis of Fluoroorganic Compounds). Object of invention It is an object of this invention to provide a method of producing 1, 1, 1, 3,3-pentafluoropropane with a good yield by using 1,1,3,3,3-pentafluoropropene as a starting material. It is a further object of this invention to provide a production method which is industrially feasible and easyly provides the starting material 1,1,3,3,3-pentafluoropropene by using 1,1,1,3,3-pentafluoro-2,3-dichloropropane as a raw material. Constitution of invention The inventors have studied methods of producing 1,1,1,3,3-pentafluoro-propane by hydrogenating 1,1,3,3,3-pentafluoropropene in a gas phase. As a result of the study, the inventors found that though the usual hydrogenation of 1,1,3,3,3-pentafluoropropene at room temperature in the presence of a palladium catalyst results in a low conversion yield, a high reaction temperature improves the conversion yield and the object material can be obtained with a high yield, thus achieving the present invention. Furthermore, the inventor found that when active carbon is used as a carrier of palladium catalyst, a selectivity of 100 percent can be attained. That is, the present invention is a method of producing 1,1,1,3,3-pentafluoro-propane with a high yield of 99 percent or more by hydrogenating 1,1,3,3,3-pentafluoropropene in a gas phase at a temperature of between 40°C to 300°C in the presence of a palladium catalyst. In the method of the present invention, it is essential to use a temperature between 40°C and 300°C to realize the said object. A temperature below 40°C lowers the conversion yield, while a temperature above 300°C causes byproduct formation and possible damage to the equipment to be used. The reaction temperature is preferably from 50°C to 200°C. As for the process of the gas phase reaction based on the present invention, such processes as the fixed bed vapor phase reaction and fluidized bed vapor phase reaction can be used. A palladium catalyst to be used in the first invention can be used by being carried on a carrier composed of at least one selected from active carbon, silica gel, titanium oxide and zirconia, preferably being carried on active carbon. The particle size of the carrier has little effect on the reaction, but it is preferably be from 0.1 to 100 mm. As for the catalyst concentration on the carrier, a wide range from 0.05 to 10 wt. percent can be used, but a concentration from 0.5 to 5 wt. percent is recommended. In the reduction reaction of 1,1,3,3,3-pentafluoro-propene with hydrogen, the ratio of hydrogen to the raw material can be changed widely, but hydrogenation is usually carried out by using at least the stoichiometric amount of hydrogen. To the total mole of the starting material, however, a considerable excess moles of hydrogen of five or more times the stoichiometric amount can be used. The excess hydrogen can be reused after being recovered. The reaction pressure is not restricted particularly. Though the reaction can be carried out under pressure, at a reduced pressure or at normal pressure, it is preferable to carry out the reaction under pressure or at normal pressure. The contact time is usually from 0.1 to 300 seconds, preferably from 1 to 30 seconds. The starting material 1,1,3,3,3-pentafluoropropene to be used in the reaction of the present invention can be obtained, for example, by dechlorinating 2,3-dichloro-1,1,1,3,3-pentafluoropropane with zinc metal under the reflux of ethanol. After the suspension of 1.5 equivalent parts of zinc metal to 2,3-dichloro-1,1,1,3,3-pentafluoropropane in ethanol was heated and refluxed, 1,1,3,3,3-pentafluoro-propene could be obtained with a yield of 90 percent by dropping 2,3-dichloro-1,1,1,3,3-pentafluoropropane into the suspension. Furthermore, 1,1,3,3,3-pentafluoro-propene can be obtained with high yields when 2-chloro-1,1,3,3,3-pentafluoropropene as a raw material is hydrogenated in the gas phase in the presence of a catalyst composed of a metal selected from palladium, platinum and rhodium. That is, 1,1,3,3,3-pentafluoro-propene can be obtained with a high yield by hydrogenating the raw material 2-chloro-1,1,3,3,3-pentafluoropropene at a temperature especially from 30°C to 450°C , in the presence of a catalyst composed of at least one metal selected from palladium, platinum and rhodium. As for the process of the gas phase reaction such processes as the fixed bed vapor phase reaction and fluidized bed vapor phase reaction can be used. A catalyst composed of at least one metal selected from palladium, platinum and rhodium should preferably be carried on a carrier composed of at least one selected from active carbon, alumina, silica gel, titanium oxide, zirconia and others. Though the particle size of the carrier has little effect on the reaction, it is preferably be from 0.1 to 100 mm. As for the catalyst concentration on the carrier, though a wide range from 0.05 to 10 wt. percent can be used, a concentration from 0.5 to 5 wt. percent is usually recommended. The reaction temperature is usually from 30°C to 450°C , preferably from 70°C to 400°C. In the reduction reaction of 2-chloro-1,1,3,3,3-pentafluoropropene with hydrogen, the ratio of hydrogen to the raw material can be changed widely, but hydrogenation is usually carried out by using at least the stoichiometric amount of hydrogen. To the total mole of the starting material, however, a considerable excess moles of hydrogen of five or more times the stoichiometric amount can be used. The reaction pressure is not restricted particularly. Though the reaction can be carried out under pressure, at a reduced pressure or at normal pressure, it is preferable to carry out the reaction under pressure or at normal pressure. The contact time is usually from 0.1 to 300 seconds, preferably from 1 to 30 seconds. The raw material 2-chloro-1,1,3,3,3-pentafluoropropene can be obtained with a good yield, for example, by dehydrochlorination of 2,2-dichloro-1,1,1,3,3-pentafluoro-propane in an aqueous solution of alkaline compounds such as potassium hydroxide. The reaction temperature is preferably be from O to 100°C . The concentration of alkali should preferably be from 10 to 70%. The reaction pressure is not restricted particularly. Though the reaction can be carried out under pressure, at a reduced pressure or at normal pressure, it is preferable to carry out the reaction under pressure or at normal pressure. 1,1,1,3,3-pentafluoropropane can be quantitatively obtained by reacting 1,1,3,3,3-pentafluoropropene obtained in this reaction with a palladium catalyst in a gas phase. 1,1,3,3,3-pentafluoropropene effectively and at low cost, can be prepared by a process in which 1,1,3,3,3-pentafluoropropene is derived with a high selectivity from 1,1,1,3,3-pentafluoro-2,3-dichloropropane which is available at low cost. That is, a further method of producing 1,1,3,3,3-pentafluoropropene is by dechlorinating 1,1,1,3,3-pentafluoro-2,3-dichloropropane with hydrogen in the presence of a metal oxide catalyst. The raw material 1,1,1,3,3-pentafluoro-2,3-dichloropropane can be easily obtained by fluorinating hexachloropropene with HF in the presence of antimony halide. In the reductive dehalogenation of 1,1,1,3,3-pentafluoro-2,3-dichloropropane the metal oxide to be used as a catalyst is preferably an oxide of at least one metal selected from iron, chromium, cobalt, copper, nickel and manganese. The metal oxide catalyst can be obtained by burning a metal hydroxide, which is precipitated by adding an alkali of aqueous ammonia or an alkali metal hydroxide in an ordinary way to an aqueous solution of a chloride, sulfate or nitrate of a metal such as chromium, iron, cobalt, copper, nickel and manganese. These metal oxide catalysts can be used alone, but a multiple oxide of several metals selected from the said metals and a mixture of several metal oxides can also be used in the reaction. These metal oxide catalysts can be used in the pressed form of granules or pellets. It is also acceptable for the catalyst to be carried on a carrier which does not participate in the reaction, for example, at least one kind of carrier selected from active carbon, alumina, aluminum fluoride, silica gel and calcium fluoride. These metal oxides are allowed to have zero valence by pretreatment with hydrogen or reduction during the reaction. As for the excess amount of hydrogen, though the reaction can be carried out when the mole ratio of hydrogen to the necessary raw material is 1 or more, in practice a ratio of 1.5 mole or more is preferable. Because excessive hydrogen reduces the contact time and reduces the conversion yield, a mole ratio of about 2 to 5 is used in practice. The reaction temperature in the reductive dehalogenation is desirably from 200°C to 400°C and can be selected properly depending on the activity of the catalyst. As the velocity of the reaction is well-known to be increased by raising the reaction temperature, a high reaction temperature is needed when using a catalyst of low activity. But when the temperature is over 400°C , the ratio of C2 and C4 compounds, which are thought to be formed by the breaking and bonding of C-C bonds, is increased to lower the selectivity. The contact time can be properly selected depending on the conversion yield set by the catalyst activity and the reaction temperature. Generally, when catalyst activity is low, the proper conversion yield can be set by extending the contact time. According to a preferred embodiment of the claimed method 1,1,1,3,3-pentafluoropropane can be produced by dechlorinating the said 1,1,1,3,3-pentafluoro-2,3-dichloropropane with hydrogen in the presence of a metal oxide catalyst and then reacting the obtained 1,1,3,3,3-pentafluoropropene with hydrogen in a gas phase in the presence of a palladium catalyst. In this embodiment of the claimed method it is desirable to use the same metal oxide catalysts with their carriers, the amount of hydrogen to be used, and reaction temperature for dechlorination as mentioned above. Industrial potential of the invention According to the present invention, 1,1,1,3,3-pentafluoropropane can be produced with a high yield because 1,1,3,3,3-pentafluoropropene is reduced by hydrogenation in a gas phase at a temperature between 40°C and 300°C in the presence of a palladium catalyst. According to a preferred embodiment of the claimed method 1,1,3,3,3-pentafluoropropene can be produced with a good selectivity by dechlorinating 1,1,1,3,3-pentafluoro-2,3-dichloropropane with hydrogen in the presence of a metal oxide catalyst. The 1,1,3,3,3-pentafluoropropene is then changed to 1,1,1,3,3-pentafluoropropane by reaction with hydrogen in a gas phase in the presence of a palladium catalyst. Furthermore 1,1,3,3,3-pentafluoropropene used as a starting material can be produced with a high yield by hydrogenating the raw material 2-chloro-1,1,3,3,3-pentafluoropropene especially at a temperature between 30°C and 450°C in the presence of a catalyst composed of at least one metal selected from palladium, platinum and rhodium. The product of this invention, 1,1,1,3,3-pentafluoro-propane, is a useful compound which can be substituted for CFCs and HCFCs which are used as refrigerants, blowing agents and cleaning agents. Examples This invention is explained in more detail through the following examples. Example 1 A SUS-316 reactor tube 7 mm in inside diameter and 15 cm long was filled with 2.3 cc of a palladium catalyst carried on active carbon at 0.5% concentration. The reactor was heated to 100°C in an electric furnace while passing nitrogen gas. After the temperature was reached, 1,1,3,3,3-pentafluoropropene was introduced into the reactor at the rate of 5.5 cm 3 /min, together with hydrogen at the rate of 14.5 cm 3 /min. The reaction temperature was kept at 100°C. The produced gas was washed with water and then analysed by gas chromatography. The results are shown in Table 1. Example 2 The same reactor as used in Example 1 was filled with 2.3 cm 3 of a palladium catalyst carried on active carbon at 0.5% concentration. The reactor was heated to 50°C in an electric furnace while passing nitrogen gas. After the temperature was reached, 1,1,3,3,3-pentafluoropropene was introduced into the reactor at the rate of 5.5 cm 3 /min, together with hydrogen at the rate of 14.5 cm 3 /min. The reaction temperature was kept at 50°C . The produced gas was washed with water and then analysed by gas chromatography. The results are shown in Table 1. Comparison example The same reactor as used in Example 1 was filled with 1.9 cc of a palladium catalyst carried on alumina at 0.5% concentration. After the reactor was kept at room temperature ( 23°C) while passing nitrogen gas, 1,1,3,3,3-pentafluoro-propene was introduced into the reactor at the rate of 5.5 cm 3 /min, together with hydrogen at the rate of 14.5 cm 3 /min. The produced gas was analysed by gas chromatography after being washed with water. The target product 1,1,1,3,3-pentafluoropropane was obtained with a conversion yield of 75.3% and selectivity of 99.9%. Example Conversion(%) Selectivity(%) Example 1 100 100 Example 2 100 100 Comparison example 75.3 99.9 This result shows that the object compound can be obtained with high conversion yield and high selectivity when the reaction is carried out based on the method of the present invention. The starting material 1,1,3,3,3-pentafluoropropene has been prepared as follows: Example 3 (Preparation of the starting material) A SUS-316 reactor tube 2 cm in inside diameter and 40 cm long was filled with 19 cm 3 of a palladium catalyst carried on active carbon at 0.5% concentration. The reactor was heated to 200°C in an electric furnace while passing nitrogen gas. After the temperature was reached, 2-chloro-1,1,3,3,3-pentafluoropropene, which had been gasified in advance, was introduced into the reactor at the rate of 32 cc/min, together with hydrogen at the rate of 128 cm 3 /min. The reaction temperature was kept at 200°C. The produced gas was washed with water and dried with calcium chloride, then analysed by gas chromatography. The results are shown in Table 2. Example 4 (Preparation of the starting material) The same reactor as used in Example 3 was filled with 18 cm 3 of a palladium catalyst carried on carbon pellets at 0.5% concentration. The reactor was heated to 250°C in an electric furnace while passing nitrogen gas. After the temperature was reached, 2-chloro-1,1,3,3,3-pentafluoropropene, which had been gasified in advance, was introduced into the reactor at the rate of 22.8 cm 3 /min, together with hydrogen at the rate of 136.8 cm 3 /min. The reaction temperature was kept at 250°C. The produced gas was analyzed by gas chromatography after being washed with water and dried with calcium chloride. The results are shown in Table 2. Example 5 (Preparation of the starting material) A SUS-316 reactor tube 7 mm in inside diameter and 15 cm long was filled with 1.9 cm 3 of a palladium catalyst carried on carbon pellets at 3% concentration. The reactor was heated to 200°C in an electric furnace while passing nitrogen gas. After the temperature was reached, 2-chloro-1,1,3,3,3-pentafluoropropene, which had been gasified in advance, was introduced into the reactor at the rate of 2.85 cm 3 /min, together with hydrogen at the rate of 17.1 cm 3 /min. The reaction temperature was kept at 200°C . The produced gas was analyzed by gas chromatography after being washed with water and dried with calcium chloride. The results are shown in Table 2. Example Conversion(%) Selectivity(%) 5FH 245fa Example 3 99.5 50.8 48.0 Example 4 99.8 47.5 51.2 Example 5 99.5 45.3 54.6 * In the table, 5FH and 245fa mean 1,1,3,3,3-pentafluoro-propene and 1,1,13,3-pentafluoropropane, respectively. The results show that the target product can be obtained with a high conversion yield and high selectivity when the reaction is carried out based on the method of the present invention. Example 6 (Preparation of the starting material) 120 g of Cr(NO 3 ) 3 .9H 2 O was dissolved in 250 ml of water. The solution, being agitated with 200 ml of 28% aqueous solution of ammonium hydroxide, was added to 400 cm 3 of heated water to precipitate the hydroxide. After being filtered, washed with pure water and dried, the precipitate was burnt at 450°C for 5 hours to yield the powder of an oxide (chromium oxide). The powder was melded to a cylindrical form of 5 mm in diameter and 5 mm in height using a tapping sold machine. 10 g of the said chromium oxide powder was filled into a reactor tube made of Hastelloy C (Φ 20 mm x 1000 mm). After the reactor was set at the reaction temperature, pretreatment was carried out in advance by passing hydrogen into the reactor at the rate of 200 ml/min for 3 hours. Then, 1,1,1,3,3-pentafluoro-2,3-dichloropropane was introduced into the reactor at the rate of 50 ml/min. The produced gas was analysed by gas chromatography after being washed with water. The selectivity and conversion yield were calculated by multiplying areas of peaks in the gas chromatography analysis by correction factors determined separately. The results are shown in Table 3. Reaction temperature Conversion Selectivity 300°C 20% 96% 350°C 48% 95% 400°C 72% 94% It was proved that the starting material (1,1,3,3,3-pentafluoropropene) can be obtained with high selectivity. Example 7 (Preparation of the starting material) The reaction was carried out in the same way as Example 6 except that a multiple oxide of copper and chromium was used as the catalyst. The results are shown in Table 4. Reaction temperature Conversion Selectivity 300°C 35% 87% 350°C 52% 85% 400°C 84% 82% The starting material was obtained with high selectivity also in this example. Example 8 (Preparation of the starting material) The reaction was carried out in the same way as Example 6 except that an oxide of iron was used as the catalyst. The results are shown in Table 5. Reaction temperature Conversion Selectivity 300°C 18% 89% 350°C 33% 86% 400°C 68% 78% The starting material was obtained with high selectivity also in this example. Example 9 (Preparation of the starting material) 87 g of Ni(NO 3 ) 2 .6H 2 O was dissolved in 250 ml of water. After adding 181 g of silica gel to the solution, the mixture was dried, then heated to 400°C to yield nickel oxide. The oxide was molded to a cylindrical form of 5 mm in diameter and 5 mm in height using a tapping sold machine. 10 g of the said catalyst was filled into a reactor tube (Φ 20 mm x 1000 mm) made of Hastelloy C. After the reactor was set at the reaction temperature, pretreatment was carried out in advance by passing hydrogen into the reactor at the rate of 200 ml/min for 3 hours. Then, 1,1,1,3,3-pentafluoro-2,3-dichloropropane was introduced into the reactor at the rate of 50 ml/min. The produced gas was analysed by gas chromatography after being washed with water. Selectivity and conversion yield were calculated by multiplying areas of peaks in the gas chromatography analysis by correction factors determined separately. The results are shown in Table 6. Reaction temperature Conversion Selectivity 300°C 21% 92% 350°C 43% 85% 400°C 72% 82% The starting material was obtained with high selectivity also in this example. Example 10 (Preparation of the starting material) 120 g of Cr(NO 3 ) 3 .9H 2 O was dissolved in 250 ml of water. After adding 181 g of silica gel to the solution, the mixture was dried, then heated to 400°C to yield oxide. The product was Folded to a cylindrical form of 5 mm in diameter and 5 mm in height using a tapping Fold machine. 10 g of the said catalyst was filled into a reactor tube (Φ 20 mm x 1000 mm) made of Hastelloy C. After the reactor was set at the reaction temperature, pretreatment was carried out in advance by passing hydrogen into the reactor at the rate of 200 ml/min for 3 hours. Then, 1,1,1,3,3-pentafluoro-2,3-dichloropropane was introduced into the reactor at the rate of 50 ml/min. The produced gas was analysed by gas chromatography after being washed with water. Selectivity and conversion yield were calculated by multiplying areas of peaks in the gas chromatography analysis by correction factors determined separately. The results are shown in Table 7. Reaction temperature Conversion Selectivity 300°C 20% 98% 350°C 46% 96% 400°C 74% 95% The starting material was obtained with high selectivity in this example. Example 11 (Preparation of the starting material) Potassium fluoride aqueous solution (5.4 moles) was added to calcium nitrate aqueous solution (2.7 moles). To the obtained slurry, copper nitrate (1 mole), nickel nitrate (1 mole) and chromium nitrate (1 mole) were added. Then, potassium hydroxide (0.1 mole) was added. The precipitated solid was filtered and dried, then heated to 400°C to yield an oxide. The product was molded to a cylindrical form of 5 mm in diameter and 5 mm in height using a tapping sold machine. 10 g of the said catalyst was filled into a reactor tube (Φ 20 mm x 1000 mm) made of Hastelloy C. After the reactor was set at the reaction temperature, pretreatment was carried out in advance by passing hydrogen into the reactor at the rate of 200 ml/min for 3 hours. Then, 1,1,1,3,3-pentafluoro-2,3-dichloropropane was introduced into the reactor at the rate of 50 ml/mint The produced gas was analyzed by gas chromatography after being washed with water. Selectivity and conversion yield were calculated by multiplying areas of peaks in the gas chromatography analysis by correction factors determined separately. The results are shown in Table 8 Reaction temperature Conversion Selectivity 300°C 35% 98% 350°C 82% 95% 400°C 91% 93% The starting material was obtained with high selectivity also in this example.

Claims: A method of producing 1,1,1,3,3-pentafluoropropanethat is characterized by reducing 1,1,3,3,3-pentafluoropropeneat a temperature between 40°C and 300°C by reacting it with hydrogen in a gas phase in the presence of a palladium catalyst. The production method as defined by claim 1, in which the palladium catalyst is carried on a carrier composed of at least one selected from active carbon, silica gel, titanium oxide and zirconia. The production method as defined in claim 2, in which the palladium concentration on a carrier is between 0.05 and 10 wt%. The production method as defined by any of claims 1 to 3, in which hydrogenation is carried out by using at least the stoichiometric amount of hydrogen to 1,1,3,3,3-pentafluoropropene. The production method as defined by any of claims 1 to 4, wherein said 1,1,3,3,3-pentafluoropropene is obtained by dechlorinating 1,1,1,3,3-pentafluoro-2,3-dichloropropane by using hydrogen in the presence of a metal oxide catalyst. The production method as defined by claim 5, in which the metal oxide catalyst to be used in the dechlorination reaction is an oxide of at least one metal selected from iron, chromium, cobalt, copper, nickel and manganese. The production method as defined by claim 5 or 6, in which the metal oxide catalyst is carried on a carrier composed of at least one selected from active carbon, alumina, aluminum fluoride, calcium fluoride and silica gel. The production method as defined by any of claims 5 to 7, in which the dechlorination reaction is carried out by using at least the stoichiometric amount of hydrogen. The production method as defined by any of claims 5 to 8, in which the dechlorination reaction is carried out at a temperature between 200°C and 400°C.

Inventors: AOYAMA HIROKAZU, NAKADA TATSUO, SEKI EIJI, YAMAMOTO AKINORI, AOYAMA, HIROKAZU, NAKADA, TATSUO, SEKI, EIJI, YAMAMOTO, AKINORI
Applicants: DAIKIN IND LTD, DAIKIN INDUSTRIES, LTD.
Application year: 1994
Main classification: C07C19
IPC codes: B01J23, C07B61, C07C17, C07C19